prac test for Chemical Reactions

[smeee]

Would anyone have a prac test that they would like to share for Yr 9 on Chemical Reactions? I have been off for 3 days and came back to "sorry about late notice but have you any ideas what we could do for an across the form prac test ?" umm...due next week
H-E-L-P !
Something easy to set up and not be messy keeping in mind we are a boys school.
Any ideas muchly appreciated

[nickyw]

You could do the following pracs:
Rctn 1
Put a piece of mg ribbon into a testtube and add a small amount of HCl.

Rctn 2
Half fill tt with copper sulfate solution and add mg ribbon.

Rctn 3
Add small amount of copper sulfate soln to a tt. Add small amount of NaOH and let tt stand for a few minutes.

[Voice]

MIXING CHEMICALS EXPERIMENT II
NAME:_________________
PARTNER:______________
DATE:_________________
AIM: To mix chemicals safely in class and to observe and record what happens.
EQUIPMENT:

 12 x Test Tubes  Test Tube Rack
 Test Tube Holder  Bench Mat
 Chemical A  Chemical B
 Chemical C  Chemical D
METHOD:

1. Put one cm. of Chemical A in to a test tube.
2. Put one cm. of Chemical B into another test tube.
3. Pour Chemical B into Chemical A.
4. Observe the test tube.
5. Repeat this experiment until each chemical has been mixed with each of the others.
6. Rinse all test tubes immediately after use.
7. At the end of your experiment put all equipment away neatly.

RESULTS:
CHEMICALS MIXED AFTER 1 SECOND AFTER 10 SECONDS
Chemical A + Chemical B
Chemical A + Chemical C
Chemical A + Chemical D
Chemical B + Chemical C
Chemical B + Chemical D
Chemical C + Chemical D

CONCLUSION:

Different reactions occur when mixing two chemicals together. Write, in your own words, what happened with these chemicals.

The chemicals used for this prac. are Lead Nitrate, Potassium Iodide, Copper Sulphate and sodium Hydroxide, all solutions. Of course, use the appropriate safety equipment e.g. safety glasses etc....

I hope this helps.

Maree

[smiley]

We've just done one with all our Yr9 classes. I set it up as "Stations of the Science Dept" - a little Catholic humour there - and the kids rotate around the benches. Kids had to observe & do & decide if the reactions were chemical or physical based on the usual criteria - was there a change in mass, was light/heat/sound given off, was a new substance made etc?

1. Sparklers. Weigh a sparkler, burn it, weigh it again. Was there a change in mass etc etc.
2. Silver nitrate. Put a curly piece of copper wire (cleaned with sandpaper) into Silver Nitrate & observe.
3. Silly putty - make a silly putty out of glue & borax etc. Is it a new substance? Why?
4. Vinegar & Bi-Carb. Record temp of 10mL vinegar. Add bicarb & record temp again. Was there a change in temp?
5. Sodium Hydrogen Carbonate. (well it's bicarb again, but we didn't tell them that!) Weigh an evap basin, add 2 spatula's of bicarb. Weigh again. Record mass of bicarb. Heat over bunsen. Weigh again. Was there a change in mass?
6. HCl & Mg. Record temp of HCl. Add Mg & record temp again. Was there a chgane in temp? Any other evidence of chem reaction?
7. ZnO. Heat ZnO in pyrex Test-tube. Note colour change. Allow to cool. Note final colour. Was it a chemical change? Why not? (Not a permanent colour change)
8. Pb(NO3)2 & KI. 2cm of KI in a test tube. Add few drops of Pb(NO3)2. What happens?

I have attached the worksheet. I hope it comes through.

[smeee]

Thank you for all the ideas...I have passed them on to the organising teacher and just waiting now to see what he decides.....then the fun begins

[RosalieM]

Just out of curiosity, what has your school done in the past? We do the same prac exams every year with only the occasional change.

[smeee]

the last couple of pracs have been tooo messy and time consuming.
The boys had NFI what they were doing as well
Thats why we are after something like KISS

[ellice]

Hi Smiley,
Those suggestions are great.
Just one question. The heating of the ZnO. It changes colour from white to yellow. What does it change to?
I need this info in case someone asks. And I like to look like I know what I'm talking about!!!
Cheers, Ellice.

[smiley]

Well! Next time ask me an easier question! "Because it does" probably doesn't cut it with enquiring minds, so here's goes:

It's to do with physics, and light absorption. When Zinc Oxide is heated, changes happen to the lattice structure of the ZnO, but they are incomplete, and defects occur. Therefore, WHEN the ZnO is hot, it absorbs light differently to when it is cold, so it appears to be yellow. However, as soons as it cools it goes back to white. It is actually possible, under great heat and pressure to produce giant ZnO crystals that are translucent, but they very rarely occur naturally.

Hope that answers the question sufficiently.

[ellice]

My goodness, I'm impressed!
Can't wait to tell the gang that one. I'm going to practise my speech tonight.
So, it would be a physical change, not chemical. Tricky!!!
Thanks Smiley.
Ellice